The invention relates to a method for raising a worm population, in which nutrition is added to a worm population containing bedding, periodically accretion is separated from the worm population, and the remaining part of the worm population is maintained as a stock population.
Such a method is known from U.S. Pat. No. 3,961,603 which discloses a device for the cultivation of earth worms, which comprises a number of stacked pans which, with the exception of the bottom pan, are provided with orifices. The bottom pan is filled with gravel and water in order to maintain the relative humidity in the device at a constant level, whereas the uppermost pan is provided with a cover. The pans are so filled with bedding, that via the orifices the worms can travel from one pan to another and are always able to reach the nutrition which is added to the uppermost pan. Periodically the uppermost pan is removed and the worms, worm eggs, castings and bedding present therein, are separated from one another. Subsequently this pan is provided with fresh bedding and is replaced in the stack as the penultimate pan towards the bottom pan. Repeated harvesting of the worms from the converted nutrition and bedding is disadvantageous in that the job is labour intensive.
A similar method is described inter alia in the book "Raising Earthworms for Profit" by E. B. Shields (7th Edition, 1978, Shields Publications, Eagle River, Wis., U.S.A.). According to the known method a wooden or concrete trough, length 2.4 ms, width 90 cms and depth 30 to 40 cms is filled with bedding material. The bedding may consist of peat, horse-dung, straw, sawdust, wood mould and/or tree-bark and an important feature thereof is that it can contain water and has only little protein food. The bedding is stocked with such a concentration of worms that the worms can easily find one another and will reproduce. A trough of the abovementioned dimensions is stocked with about 100,000 worms. Suitable are, for example, earthworms such as Lumbricidae, Eiseniae, Allolobophorae, Dendrobaenae and the African night-crawler. After a period of ten days to one month the worms will seek food and come upwards. The nutrition is frequently deposited on the bedding and may be formed by organic refuse, dung, composte, sewerage mud, if necessary completed with commercially available food such as ground poultry fodder. After about two months the number of worms has doubled and the worm population has to be split up. For this purpose a further trough is half filled with bedding material and it is half filled of the worm-containing bedding from the first trough. Subsequently the remaining half of the initial trough is completed with new bedding material. This splitting-up process may be repeated about three times. After about six months the bedding of the initial trough contains such a large quantity of worm excrements that the worms living in this trough have to be separated from the bedding. Repeated splitting up the bedding in a trough containing a worm population has the disadvantage that the worms are disturbed, which adversely affects their behaviour. Additionally, gathering the worms from the worked-up nutrition and the bedding material is a labour-intensive process.